1. Field of the Invention
The field of art to which this invention relates is surgical instruments, in particular, electrosurgical cutting and grasping instruments.
2. Description of the Related Art
Surgery requires the use of surgical instruments within a restricted and unusually sensitive operating field. During surgery, the field becomes crowded if a large number of surgical instruments must be used simultaneously, with concomitant difficulty for the surgical team to maintain a clear viewing area. Under such circumstances, surgical instruments designed to perform more than one task are of particular importance.
Two techniques used extensively in both open and endoscopic surgery are (a) the controlling of bleeding using electrosurgical instrumentation and (b) the incision or severing of tissue or vessels. The control of bleeding during surgery accounts for a major portion of the time involved in surgery. In particular, bleeding that occurs when tissue is incised or severed can obscure the surgeon's vision, prolong the operation, and adversely effect the precision of cutting. Blood loss from surgical cutting may require blood infusion, thereby increasing the risk of harm to the patient.
Hemostatic electrosurgical techniques are known in the art for reducing bleeding from incised tissue prior to, during, and subsequent to incision. Electrosurgical cutting and coagulating instruments are used to perform such techniques. These instruments can be of a reusable type (which require cleaning and disinfecting or sterilizing before each use) or disposable (which are disposed of after a single use). Each type includes both monopolar and bipolar variations having at least one electrode. Radio frequency (RF) energy is conducted through this electrode to either a remote conductive body-plate (known as a grounding pad) in the case of monopolar instruments, or to a second, closely spaced conductive electrode in the case of bipolar instruments. In monopolar instruments electrical current travels from the electrode through the patient's body to the grounding pad. Bipolar instruments are typically connected to both poles of an electrosurgical generator, therefore current flow is typically limited to tissue adjacent to the working end of the bipolar instrument (where the two electrodes are located).
Prior to the advent of electrosurgical cutting instruments, a surgeon would perform any cutting with a scissors and coagulate with an entirely different instrument. This exchange of instrumentation was time consuming. In response for the need to have a scissors-type instrument for cutting but which also incorporated the ability to coagulate blood and other body tissue using RF energy, electrosurgical cutting devices have been developed which combine mechanical cutting with electrosurgical cauterization, coagulation, and cutting.
Standard shape and size scissors have evolved in the surgical arts which surgeons have become accustomed to. These standards have been incorporated into the electrosurgical cutting instruments, not only because they have been tested by time and found to be very functional, but mainly because surgeons have become accustomed with their feel and use. Examples of some of these standards include the Mayo, Metzenbaum, and Tenotomy scissors. Each standard scissor is typically available in both curved and straight variations.
Grasper or forcep type instruments are also well known in the art. They generally consist of opposing jaws which pivot about a pivot point into an open or closed position. In a closed position the jaws of the grasper provide a means to grasp and hold, or grasp and tear, a piece of body organ, a vessel, or tissue.
Electrosurgical graspers have been developed to cauterize a portion of tissue. This is accomplished in one of two ways. Cauterization can be accomplished by using an outside surface or the tip of both jaws to cauterize the tissue the jaws contact. Cauterization can also be accomplished with a grasper by grasping down onto tissue and cauterizing the tissue between the jaws. It is in this way that electrosurgical graspers are used to coapt a vessel prior to transection with a cutting device. Electrosurgical graspers are also used to coapt retracted bleeders (severed blood vessels).
In practice, vessels are coapted in several ways. One such way is by using a standard grasper not capable of cauterization and a monopolar pencil. The vessel is first clamped between the jaws of the grasper, and the pencil is used to energize the grasper with RF energy. The RF energy passes from the monopolar pencil, through the forceps, vessel and patients body to the grounding pad. This is a potentially dangerous procedure. The patient or surgeon can be easily injured in such a procedure.
Another way to perform coaptation of vessels is by using a monopolar or bipolar scissors in which the scissors are rotated exposing the vessel to the side surfaces of the scissor's blades. In theory, the blade sides cauterize the vessel and the vessel is then severed with the scissors. In practice, this procedure is very difficult and can lead to complications. It is very easy for a surgeon to nick the vessel with the scissor blades before the coaptation of the vessel is complete, causing unanticipated bleeding and the need for further instrumentation to stop the bleeding.
Whichever method of coaptation is used, subsequent to the coaptation, the vessel is severed by a cutting instrument such as an electrosurgical scissor. In light of the above discussion, this procedure has been most effectively and safely accomplished with at least two different surgical instruments, a grasper to grasp and coapt, and a scissor to sever the coapted vessel.
Tidemand, U.S. Pat. No. 5,342,381, discloses an endoscopic combination bipolar scissors and forceps instrument which has blade and forceps portions on each of two jaws. Although the Tidemand instrument is useful it is subject to several disadvantages which effect the performance of the device, especially with regard to coaptation of vessels.
Since the blades of the Tidemand invention are insulated (typically ceramic) the blades themselves only offer mechanical cutting. As discussed previously, an instrument which offers both mechanical and electrosurgical cutting is preferred over one which offers only the former. Additionally, certain procedures require that the scissors portion of the instrument be distal to the graspers. Likewise, some procedures require the grasper portion of the instrument to be distal to the scissor portion. Tidemand discloses only the latter configuration, which is inadequate in many surgical procedures.
Furthermore, the shape and size of the cutting and grasping surfaces in the Tidemand instrument are awkward, unlike any standard scissor that surgeons have become accustomed to.
With regard to surgical procedures in which coaptation of vessels is required, the Tidemand combination instrument could not be effectively utilized. Effective coaptation requires hemostasis during cutting as well as during grasping (or clamping) in order to cauterize the ends of the severed vessel.
Like the Tidemand instrument, the single feature electrosurgical cutting devices and graspers of the prior art are useful and effective, but they too suffer from several deficiencies associated with their use. The instrument exchange associated with cutting, coagulating and coaptation requires dexterity on the part of the surgeon. The increased number of instruments has the disadvantage of crowding the operating field. Additionally, their is a greater burden on assistant personnel in the operating room, such as nurses, because of the exchange of instrumentation between them and the surgeon.
Another disadvantage of the prior art concerns cleaning, disinfecting and sterilization (CDS) issues known in the surgical instrumentation art. Transmission of sickness and disease through contaminated instrumentation is a very real problem in the medical field. Typically, surgical instrumentation is cleaned and disinfected or sterilized after each use to minimize this possibility. Since effective coaptation of vessels has required two instruments, a graspers and a scissors, the risk of disease transmission is increased. The explanation for this is purely statistical, the probability of transmitting disease in two instruments is greater than for a single instrument.
Additionally, the cost of processing (cleaning, disinfecting or sterilizing) two reusable instruments and purchasing two reusable instruments is greater than the costs associated with a single combined instrument.
To combat the CDS problems associated with reusable instruments, disposable instruments have been developed which are disposed after a single use. While they have their advantages, disposable instruments suffer from the disadvantage of contributing to the amount of medical waste generated.
The prior art disposable scissors and graspers suffer the disadvantage of contributing twice the medical waste as a single disposable instrument combining both features. Likewise, the cost of two disposable surgical instruments is greater than the cost of a combined disposable instrument.
Accordingly, there is a need in the art for an improved electrosurgical instrument having mechanical grasping and cauterization capabilities to coapt vessels combined with capabilities to mechanically transect and cauterize the vessel, contained within a standard scissors shape and size.